A cable with multiple strands can be welded to a terminal by means of several welding techniques, e.g. compaction welding. By the development of laser techniques, some solutions for laser welding of cables or wires to terminals were developed, which are discussed hereunder.
In U.S. Pat. No. 4,774,394 a laser welding technique is disclosed, wherein a single metallic conductor wire is welded to a U-shaped metallic fixture using a laser. In the method the end section of a single wire is placed into a fixture and is welded to it by means of a laser beam directed to the end of the wire.
In U.S. Pat. No. 5,541,365 and JP 59-1 07786 A laser welding methods are disclosed, in which a single wire is welded to a U-shaped terminal by means of a laser beam.
In U.S. Pat. No. 6,531,676 B2 a laser welding method is disclosed, in which a single wire is welded to a U-shaped carrier or terminal made of copper.
In U.S. Pat. No. 7,128,620 B2 a laser welding method of a cable of multiple strands to a terminal is disclosed. The multiple strands are compacted and shaped before inserted into a slot of the terminal.
In U.S. Pat. No. 4,966,565 and U.S. Pat. No. 7,705,265 B2 laser welding methods are disclosed, wherein the multiple strands of a cable are crimped to the terminal before the strands are welded to it. The target point of the laser beam is chosen differently in the two documents.
The methods disclosed in the above documents have several disadvantages. On the one hand, in the prior art methods a groove or a recess is needed for the laser welding even in the simplest case of a single wire. On the other hand, cables of multiple strands are laser-welded only after an additional compaction or crimping step used for keeping each of the strands together.
In the light of the known methods disclosed in the above documents, it is an object of the invention to provide a method for laser welding of a cable of multiple strands to a terminal, where neither crimping of the strands nor other shaping or compaction of the strands is needed. It is also an object of the invention to provide a laser welding method which is exempt from the disadvantages of the prior art solutions.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.